Wiring substrate, wiring board, and wiring substrate mounting structure

Abstract

In a wiring substrate, a high-frequency component is carried on a dielectric board having a transmission line formed on its surface, a reverse surface of the dielectric board is formed with an opening in a predetermined cross-sectional shape, and a high-frequency connecting pad is formed around the opening. In the wiring board, a dielectric board penetrates a waveguide structure and has its inner wall coated with a conductor, and a high-frequency connecting pad is formed on a surface of the dielectric board. The wiring substrate is placed on the wiring board, and the respective high-frequency connecting pads are electrically connected to each other, to fabricate a module. Even when a low-cost material having a large dielectric loss tangent is used for the wiring board, a high-frequency signal can be prevented from being attenuated.

Description

[0001] This application is based on application No. 2000-361749 filed in Japan, the content of which is incorporated hereinto by reference.[0002] 1. Field of the Invention[0003] The present invention relates to a wiring substrate used in a microwave region or a millimeter wave region, a wiring board, and a wiring substrate mounting structure.[0004] 2. Description of the Related Art[0005] It has been examined whether or not an electric wave is made use of for transmitting information from a microwave region of 1 to 30 GHz to a millimeter wave region of 30 to 300 GHz. An electric wave application system using a millimeter electric wave, for example, a radar between vehicles has been put to practical use.[0006] As an example of electric components using such high frequencies, a wiring substrate accommodating a plurality of chips in its one case is assumed.[0007] FIG. 6 is a schematic sectional view for explaining the structure of such a wiring substrate 60. In FIG. 6, a metal case 61 a...

AI Technical Summary

Benefits of technology

[0014] The inventors of the present invention have incorporated into a wiring substrate a matching section for a transmission line such as a microstrip line in a wiring substrate to match with the exterior, and further incorporated a waveguide structure which can be coupled to the matching section into a wiring board. They have found that even when a low-cost material having a large dielectric loss tangent is used for the wiring board, a high-frequency signal can be prevented from being attenuated, to make the present invention.

[0016] According to the wiring substrate, the matching section for taking out a signal flowing through the transmission line such as the microstrip line is incorporated into the wiring substrate, thereby making it possible to convert the high-frequency signal into an electromagnetic wave in a waveguide mode and feed the electromagnetic wave to the exterior.

[0019] According to the wiring substrate mounting structure, the wiring substrate and the wiring board are connected to each other through the high-frequency connecting pads respectively formed therein, thereby making it possible to transmit the high-frequency signal by the waveguide mode between the wiring substrate and the wiring board. Even if a material having a small dielectric loss tangent is not used as a material for the wiring board, therefore, it is possible to realize high-frequency transmission having a low loss between the wiring substrates or between the wiring substrate and the external circuit. Further, a low-cost material for the wiring board is used, and quantity production is improved by surface mounting, thereby making it possible to obtain a high-frequency module having good characteristics and low in cost.

Problems solved by technology

Consequently, the wiring board has been conventionally fabricated using a low-loss material having a small dielectric loss tangent, for example, high-purity alumina, resulting in increased cost.

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